The present invention relates to a system and a method for operating an emission treatment system, and more particularly to supplying reductants to an emission treatment system to improve its NOx conversion efficiency.
Current emission control regulations necessitate the use of emission treatment systems to reduce catalytically nitrogen oxides (NOx) produced during engine operation into harmless exhaust gases in the exhaust systems of combustion powered vehicles, including locomotives, trucks, cars, and the like. These catalytic emissions treatment systems often use a reducing agent or reductant that is introduced into the diesel exhaust stream before the exhaust stream enters the system for treatment. Typical reducing agents may include light hydrocarbons and oxygen bearing compounds like alcohols.
Known methods of supplying the reductants may involve supplying the reducing agents and the fuel separately or may involve chemically producing the reducing agent in situ from the fuel itself. Such methods typically employ complex subsystems such as special purpose pumps, filters, storage tanks and the like. Additionally, these systems also require valuable space and specialized materials, thereby involving additional expenses. Therefore, there is need for an improved system and method for supplying the reductants to provide better overall economy and ease of operation.